The subject matter disclosed herein relates to the gasification of materials, and, in particular, to a cooled throat plug for a gasifier vessel, the throat plug including an instrumentation cavity.
Gasification is a partial oxidation process that converts carbonaceous materials, such as coal, petroleum, or biomass, into carbon monoxide and hydrogen by reacting the raw material at high temperatures with a controlled amount of oxygen and/or steam. The resulting gas mixture is called synthesis gas or “syngas”, which itself is a fuel. Gasification is a relatively efficient method for extracting energy from many different types of organic materials, and also has application as a clean waste disposal technique.
An advantage of gasification is that use of the syngas is relatively more efficient than direct combustion of the original fuel. As a result, more of the energy contained in the fuel is extracted. Syngas may be burned directly in internal combustion engines, used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process into synthetic fuel. Gasification can also begin with materials that are not otherwise useful fuels, such as biomass or organic waste. In addition, the high-temperature combustion refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels.
Gasification of fossil fuels is currently widely used in electricity generation. For example, the syngas can be cleaned and then sent to a gas turbine/steam turbine combined cycle system where it is used to generate electricity. Pollution causing emissions are captured and cost effectively removed from the syngas stream before combustion. Thus, the overall system converts, e.g., coal into a cleaner burning fuel for generation of electricity therefrom. Such an overall system is oftentimes referred to as an integrated gasification combined cycle (IGCC) system.
Almost any type of organic material can be used as the raw material for gasification, such as wood, biomass, or even plastic waste. Thus, gasification may be an important technology for renewable energy. In particular biomass gasification can be carbon neutral.
Gasification of fossil fuels typically takes place in a chamber or refractory vessel called a gasifier vessel, which commonly is an internally coated metal stricture. Gasifier vessel floors typically include an inverted frusto-conical throat to allow synthesis gas to flow out of the gasifier vessel. A metal gasifier floor supports refractory material, such as a ceramic brick, that covers the metal floor and also supports the refractory material that covers the inner surface of the gasifier vessel.
Instrumentation in a gasifier vessel is typically limited to thermocouples and skin temperature sensing devices due to the inability to access the internal process (i.e., conversion of coal to syngas) taking place within the gasifier vessel. The internal process operates at relatively high temperature and pressure in a corrosive environment, thereby making it difficult to insert typical sensor arrays into the vessel. Instrumentation has traditionally been inserted through the brick refractory on the side of the vessel, and in general has been limited to thermocouples. Other methods of temperature sensing have been used industry wide to gather surface temperatures of gasifier vessels.
Injection of various fuels, and streams of foreign material into the gasifier vessel usually requires a separate piece of equipment for natural gas burners, or injection of tracer streams in the slurry line considerably upstream of the injector. Point of operation injection is difficult to conduct. For injection, it is industry practice to swap injector devices. For example, a plant will have an injector for natural gas for bringing the refractory brick up to temperature and an injector for the injection of the fuel to create syngas.